Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 658 PM EDT Mon Jun 27 2022 Valid 12Z Fri Jul 01 2022 - 12Z Tue Jul 05 2022 ...Overview... An upper high and warm upper ridging will be in place across eastern Alaska and northwestern Canada through the end of the week, while an upper low drifts toward far eastern Russia embedded within large scale troughing over the Bering Sea. Additionally, an energetic shortwave rounding the southern side of the trough is forecast to pass near the Aleutians late week and into the Gulf of Alaska early next week. Moist southerly flow, this shortwave energy, and a surface low pressure/frontal system will spread increasing rain chances generally from west to east across Alaska through the weekend. Areas influenced by the troughing, particularly southwestern Alaska, should also see cooling temperatures, but warmer than normal temperatures may persist in eastern Alaska into early next week. ...Guidance Evaluation/Predictability Assessment... Recent model guidance was in good agreement with an upper low initially over the Bering Sea. The trend has been for this feature to drift away from Alaska, and model guidance is agreeable that it drifts northwestward into eastern Russia and then meanders there. Thus the energetic shortwave passing farther south near the Aleutians may be more relevant for disrupting the hold of ridging over at least the western part of the state. The model consensus is for energy possibly forming a separate upper low to split off as it crosses into the Gulf of Alaska by early next week, but with potential to shift the upper high farther east into Canada. There seemed to be reasonably good agreement through early next week with no notable outliers in the 12Z cycle, so could use a blend of deterministic guidance for the WPC forecast. As usual, models diverge with the details by the later forecast times, including strength and placement of the Gulf upper low by that time as well as amount of phasing with the flow to the north. Thus gradually phased in more EC/GEFS ensemble mean guidance to half the blend by day 8. ...Weather and Hazard Highlights... Temperatures will continue to be rather warm across about the northeastern two-thirds of the mainland Friday, generally 10-20F above normal under the upper ridge, while southwestern Alaska starts to cool to below normal for high temperatures given the troughing/low aloft. Cooler temperatures are forecast to gradually filter north and eastward through the weekend and into early next week, with near to below average highs though lows may stay near to above normal. The far eastern mainland and parts of the Panhandle may stay above average into early next week if the ridge stalls. Just ahead of the trough and a surface low pressure/frontal system, moisture will increase given the southerly flow and lead to rainfall chances first for western Alaska and spreading eastward through the weekend. The Alaska Peninsula and Kodiak Island and possibly into the southwestern mainland and parts of the Kenai Peninsula are likely to see the heaviest rainfall amounts. Rain totals are expected to lessen farther north and east but showers are possible across much of the mainland. By early next week, the Brooks Range and North Slope may see enhanced (though still relatively light) precipitation amounts with a front across the region. Tate Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php Hazards: - Heavy rain across portions of southern Alaska, Fri-Sat, Jul 1-Jul 2. - Much above normal temperatures across portions of mainland Alaska, Fri-Sun, Jul 1-Jul 3. WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html